Exploring the Role of Cereal Dietary Fiber in Digestion

Peasant vs. Industrial durum wheat pasta: Impact of each processing step on protein solubility and digestibility

Some people with Non-Coeliac Gluten (or Wheat) Sensitivity (NCGS) declare that they can consume peasant pasta without the usual inconvenience they experience after eating industrial pasta. The main differences between peasant and industrial pasta lie in the varieties used (old vs. modern), and the production chain (grain milling, semolina hydration and mixing, extrusion or lamination, drying and packaging). Yet, the varieties, the material and the method used by the peasants and by the industrial sector to make pasta differ at each stage. The impact of each of these stages was analyzed on protein quantity and quality from semolina to cooked pasta. Grown in the same conditions, the old variety (cv. Bidi 17) used by farmers contained much more protein than the modern variety (cv. Anvergur) recommended by industry and its pasta was better-digested in-vitro. Focusing on cooked pasta, milling had a great impact on not easily soluble proteins (DTE-soluble proteins): pasta made from stone-milled grains (peasant method) had less DTE-soluble proteins than pasta made from roller-milled grains (industrial method) and a higher amount of in-vitro digested proteins. The mixing and extrusion step mainly affected the easily soluble proteins (SDS-soluble proteins). The amount of such proteins was greater for farmer cooked pasta (non-monitored extrusion) than for industrial ones (monitored extrusion). Concerning the drying step, the proportion of SDS-soluble proteins was higher for the pasta dried at low temperature (peasant method), compared to high temperature (industrial method). Thus, the observation that peasant cooked pasta would be more digestible than industrial pasta seems to be due mainly to variety (61%), to a lesser extent to grinding on a stone-mill (22%) and extrusion on non-monitored conditions (16%) and finally a little (1%) to drying at low temperature and therefore longer.

Increasing fibre in white flour and bread: Implications for health and processing

Dietary fibre is beneficial for human health, but dietary intakes are below recommended levels in most countries. Cereals are the major source of dietary fibre in Western diets, with bread providing about 20% of the daily intake in the United Kingdom. Despite the promotion of fibre-rich wholegrain products, white bread (which has a lower fibre content) remains dominant in many countries due to cultural preferences. Increasing the fibre content of white bread and other products made from white flour is therefore an attractive strategy for increasing fibre intake. This can be achieved by exploiting genetic variation in wheat without major effects on the processing quality or the consumer acceptability of products. Modelling data for food consumption in the United Kingdom shows that increasing the fibre content of white flour by 50% (from about 4% to 6% dry weight) and in wholegrain by 20% will increase total fibre intake by 1.04 g/day and 1.41 g/day in adult females and males, respectively. Furthermore, in vitro studies indicate that the increased fibre content of white bread should reduce the rate of starch digestion and glucose release in the human gastrointestinal tract.

Genetic Approaches to Increase Arabinoxylan and β-Glucan Content in Wheat

Wheat is one of the three staple crops feeding the world. The demand for wheat is ever increasing as a relatively good source of protein, energy, nutrients, and dietary fiber (DF) when consumed as wholemeal. Arabinoxylan and β-glucan are the major hemicelluloses in the cell walls and dietary fiber in wheat grains. The amount and structure of DF varies between grain tissues. Reducing post-prandial glycemic response as well as intestinal transit time and contribution to increased fecal bulk are only a few benefits of DF consumption. Dietary fiber is fermented in the colon and stimulates growth of beneficial bacteria producing SCFA, considered responsible for a wide range of health benefits, including reducing the risk of heart disease and colon cancer. The recommended daily intake of 25-30 g is met by only few individuals. Cereals cover nearly 40% of fiber in the Western diet. Therefore, wheat is a good target for improving dietary fiber content, as it would increase the fiber intake and simultaneously impact the health of many people. This review reflects the current status of the research on genetics of the two major dietary fiber components, as well as breeding approaches used to improve their quantity and quality in wheat grain.

Farmer vs. Industrial Practices: Impact of Variety, Cropping System and Process on the Quality of Durum Wheat Grains and Final Products

The consumption of artisanal and organic pasta made on-farm from ancient varieties is increasing in France. Some people, namely, those suffering from digestive disorders following the consumption of industrial pasta, consider these artisanal pasta to be more digestible. Most of them have linked these digestive disorders to the ingestion of gluten. We analyzed in this study the impact of industrial and artisanal practices on the protein quality of durum wheat products. The varieties recommended by the industry (IND) were compared to those used by farmers (FAR): the FAR being on average much richer in protein. However, the solubility of these proteins analyzed by Size Exclusion-High Performance Liquid Chromatography (SE-HPLC) and their in vitro proteolysis by digestive enzymes vary little between the two groups of varieties, while differences between varieties in each group are observable. The location of grain production and the tested cropping systems (zero vs. low input) have a low impact on protein quality. Yet, more contrasting modalities should be studied to validate this point. The type of production process (artisanal vs. industrial) is, among those studied, the factor having the greatest impact on protein compositionPasta produced by the artisanal method contains a higher sodium dodecyl sulfate (SDS)-soluble protein fraction and are more in-vitro proteolyzed. Whether these criteria are indicative of what happens during a consumer's digestion remains to be determined. It also remains to be assessed which key stages of the process have the greatest influence on protein quality.

Dietary Supplementation With Fine-Grinding Wheat Bran Improves Lipid Metabolism and Inflammatory Response via Modulating the Gut Microbiota Structure in Pregnant Sow

This study investigated the effects of fine-grinding wheat bran on pregnant sow body condition, lipid metabolism, inflammatory response, and gut microbiota. In this study, wheat bran was crushed into three particle sizes. A total of 60 Landrace × Yorkshire second parity sows were allotted to two groups: CWB (a diet containing coarse wheat bran with particle size of 605 μm) and FWB (a diet containing fine wheat bran with particle size of 438 μm). Fine-grinding wheat bran had higher soluble dietary fiber concentration, swelling capacity, water-holding capacity, and fermentability than coarse wheat bran. Pregnant sows fed FWB throughout pregnancy had lower body weight and fat deposition than sows fed CWB. And the piglet body weight at birth of the FWB group was remarkably increased. Serum concentrations of lipids (triglycerides, total cholesterol, and free fatty acid), interleukin 6, leptin, and resistin were decreased on day 90 of pregnancy by fine wheat bran supplementation. Feeding FWB significantly decreased abundance of Firmicutes and dramatically increased the abundance of Bacteroidetes at phylum level. At genus level, the abundance of Terrisporobacter was decreased in FWB feeding sows, but the abundance of Parabacteroides was increased. Fecal total short-chain fatty acids, propionate, and butyrate contents were markedly increased in the FWB group. The results suggested that the physicochemical properties of finely ground wheat bran had been improved. Dietary supplementation with fine wheat bran changed the gut microbiota structure and enhanced the short-chain fatty acids level, which improved the maternal body condition, metabolic and inflammatory status, and reproductive performance in sows.

Interventional effect of dietary fiber on blood glucose and pregnancy outcomes in patients with gestational diabetes mellitus

To investigate the effect of dietary fiber on blood glucose and pregnancy outcomes in patients with gestational diabetes mellitus (GDM). One hundred and twelve patients with GDM in the second trimester of pregnancy were recruited from Women's Hospital, Zhejiang University School of Medicine. Patients were randomized into two groups with 56 in each group: the control group received basic nutrition support; while the dietary fiber group were given additional dietary fiber ( total dietary fiber per day) before meals in addition to basic nutrition support. Intervention for all cases lasted for 8 weeks. Fasting blood glucose and postprandial blood glucose (2 h BG) were measured every week, and oral glucose tolerance test (OGTT) was performed at 42 d postpartum to evaluate the glycemic outcomes. Perinatal outcomes were recorded. The dietary fiber intervention markedly improved 2 h BG in patients with GDM and significantly elevated the glucose compliance rate from the 3rd to 8th week compared to the control group ( <0.05 or <0.01). OGTT 2 h glucose and the incidence of impaired glucose tolerance in the dietary fiber group were significantly lower than those in the control group, while the glucose compliance rate was significantly higher than that in the control group (all <0.01). Moreover, the rates of adverse perinatal outcomes, such as premature rupture of membranes and neonatal hyperbilirubinemia were declined in the dietary fiber group (<0.05 or <0.01). Dietary fiber intervention can ameliorate hyperglycemia in GDM patients, improve perinatal outcomes and reduce the incidence of postpartum impaired glucose tolerance.

Human Exposure to Toxic Metals (Al, Cd, Cr, Ni, Pb, Sr) from the Consumption of Cereals in Canary Islands

The Canary Islands is an archipelago that consumes cereals and derivatives imported from other regions of the world. The increase in contamination with toxic metals makes it necessary to assess the content of toxicological metals of interest to ensure quality and safety. The content of toxic metals (Al, Cd, Cr, Pb, Ni, Sr) was determined in 221 samples of cereals and derivatives (corn, wheat, gofio, corn gofio, barley gofio, roasted corn and flour) marketed in the Canary Islands using ICP-OES (inductively coupled plasma optical emission spectrometry) to assess dietary exposure. Al content recorded in barley gofio (29.5 mg/kg fresh weight) stands out. The estimated daily intake (EDI) of Pb is 52 µg/day if 100 g/day of barley gofio is consumed (121% and 240% of the BMDL nephrotoxicity limit set by the EFSA at 0.63 µg/kg body weight/day for adults and children, respectively). The EDI of PB is 16 µg/day if 30 g barley gofio/day is consumed by adults (36.2% of the abovementioned BMDL nephrotoxicity limit). The EDI of Pb is 7.8 µg/day if 15 g barley gofio/day is consumed by children (32.2% of the abovementioned BMDL nephrotoxicity limit). Gofio is a food of high nutritional value. It is necessary to establish monitoring programs for toxic metals in raw materials and processed products to reduce exposure levels.

Strategies to improve wheat for human health

Despite their economic importance and growing demand, concerns are emerging around wheat-based foods and human health. Most wheat-based foods are made from refined white flour rather than wholemeal flour, and the overconsumption of these products may contribute to the increasing global prevalence of chronic diseases, particularly type 2 diabetes and obesity. Here, we review how the amount, composition and interactions of starch and cell wall polysaccharides, the major carbohydrate components in refined wheat products, impact human health. We discuss strategies and challenges to manipulate these components for improved diet and health using newly developed wheat genomics tools and resources. Commercial foods developed from these novel approaches must be produced without adverse effects on cost, consumer acceptability and processing properties.

Effect of the Addition of Soluble Dietary Fiber and Green Tea Polyphenols on Acrylamide Formation and In Vitro Starch Digestibility in Baked Starchy Matrices

Starch digestibility may be affected by food microstructural changes, as well as by specific interactions with some biomolecules, such as soluble dietary fibers (SDFs). It is well-known that acrylamide (AA) is a toxic and potentially carcinogenic compound formed in starchy food products processed at temperatures above 120 °C. This study aimed to investigate the effect of the addition of SDF and green tea polyphenols (GTP) on AA formation and in vitro starch digestibility in baked starchy matrices. The formulations were prepared using gluten and wheat starch, ensuring ~40 ± 2% (wet basis, w.b.) moisture in the doughs. In some samples, 7.5% (dry basis, d.b.) of starch was replaced with inulin (IN), polydextrose (PD) or partially hydrolyzed guar gum (PHGG), and/or with GTP at 1% (d.b). Acrylamide was determined by gas chromatography–mass spectrometry, and the in vitro starch digestibility using the Englyst method. The GTP was able to reduce AA content by ~48%, and a combination of IN-GTP allowed it to be reduced by up to ~64%, revealing the lowest rapidly available glucose content (~17 mg/g glucose). While a PD-GTP mixture reduced the AA content by around ~57% and gave the highest unavailable glucose fraction (~74 mg/g glucose) compared to the control. This study showed how functional ingredients could be used to develop successfully healthier starchy bakery foods.